Container and package utilizing the same



Aug. 23, 1966 G. G. KAMM CONTAINER AND PACKAGE UTILIZING THE SAME INVENTOR.

A my@ f4 A N @d wm United States Patent O M 3,268,344 CONTAINER AND PACKAGE UTLIZING THE SAME Gilbert George Kamm, Barrington, lll., assignor to American Can Company, New York, N.Y., a corporation of New Jersey Filed Jan. 19, 1965, Ser. No. 429,199 7 Claims. (Cl. 99-181) This application is a continuation-impart of my copending application Serial No. 246,908, filed December 26, 1962, now abandoned.

This invention relates to an enameled tinplate container having a particular construction to prevent undesirable redox reaction between the metal of the :container and certain relatively corrosive products packed therein, and to a package including this container and these products. More specifically it relates to an enameled tinplate container having a particular soldered side seam to substantially inhibit if not obviate chemical attack upon the steel base metal of the can by the product and the undesirable results of such an attack.

The products for which the can construction of the instant invention has primary utility as a container are those subject to tannate discoloration such as asparagus, green beans, okra, cranberries and the like, and tomato products, particularly tomato paste, and prunes. While the complex chemical composition of each `of these products may and very probably does differ, each is considered to have a relatively high degree of corrosivity with respect to a tinplate can in which they are packed. Further, the general nat-ure of the attack on the metal of the can with each of these products is substantially the same. Each of these products is capable of attacking both the tin and steel of the tinplate can directly. When sutlicient tin is exposed to the product, it acts as a sacrificial anode and provides cathodic protection to the steel thereby preventing direct attack of the steel by the product. However, concurrently with the cathodic protection of the steel by the tin causing it to go into solution, the product is directly attacking and dissolving the tin exposed. In most instances, the direct attack of =the tin overshadows the galvanic corrosion resulting from the tin-steel couple action. This direct attack on the tin proceeds at a rate which is a function of the surface area of tin exposed; and even with the surface tin coating weights commercially available, the rapid detinning of the interior surface of the can takes place in too short a time period to make a plain tinplate can wholly acceptable for the commercial packaging and marketing of these products.

Rapid, uneven detinning exposing areas of tin-iron alloy results in an unsightly appearance, even before all of the tin has been corroded from the plate surface.

By the time the tin is essentially all removed from the steel base metal, the product is attacking the steel itself. Such a direct attack upon the steel leads to an exceedingly unsightly appearance on the interior of the can, and hydrogen swells or perforations of the can side wall if it is allowed to proceed long enough. In the case of products susceptible to tannate discoloration, the ferrous ions released into the product, through a complex chemical reaction, cause a darkening or blackening of the product itself upon exposure to the air after opening. In other Words, the package including a plain tinplate can enclosing one of the products enumerated above, in most instances, would be completely unmarketable within the time period needed to pack, warehouse, distribute and retail the package.

It is therefore an object of the instant invention to provide a tinplate can having a novel side seam construction which eliminates the problems set forth above.

3,268,344 Patented August 23, 1966 ICS Another object is to provide a tinplate can for the packaging of relatively highly corrosive products wherein the resulting package has a commercially acceptable shelf life.

Yet another object is to provide a tinplate can which simply and efficiently inhibits undesirable redox reactions between the metal of the .can and the product' packed therein.

Still a further object -is to provide a package hav-ing a long shelf life with no undesirable chemical inter-reaction between a packed product and the metal of the can when the product has a relatively highly corrosive character in relation to the can metal.

Numerous other objects and advantages of the invention will be apparent as it is better understood fro-m the following description, which, taken in connection with the accompanying drawings, discloses a preferred embodiment thereof.

The above objects are accomplished by providing a tinplate can having an organic coating or enamel over substantially the entire interior surface thereof and having its longitudinally extending side seam bonded and hermetically sealed by means of pure tin soft solder wherein the tin solder forms a illet of appreciable size along the side seam on the inside of the can and is exposed to a relatively highly corrosive product packed in the can.

Referring to the drawings:

FIG. 1 is a perspective view of a sheet metal can with a portion thereof broken away, exposing the interior of the can;

FIG. 2 is an enlarged fragmentary sectional view taken substantially along lines 2 2 4in FIG. 1; and

FIG. 3 is an enlarged fragmentary sectional View taken substantially along lines 3-3 in FIG. l.

As a preferred or exemplary embodiment of the instant invention, FIG. l illustrates a hermetically sealed metal container, generally designated 20, having a body 22 with a longitudinally extending vented side seam 24. The body 22 is closedby upper and lower ends 25, 26, respectively, which are made integral with the body 22 by any suitable means such as upper and lower doubleseams 27, 28 respectively. U.S. Patent No. 2,064,537, describes a type .of container suitable for this invention.

Prior to the attachment of either end 25 or 26, the side seam 24 of the body 22 is hermetically sealed by being filled with substantially pure tin solder 31, which is applied from the outside of the container 20, in a manner well known in the art.

In the three-thickness zone (FIG. 2), the solder flows in between a body wall part 34 and a hook 36 and also in between the outer surface of the latter and the outside body Wall 38. It also iiows laterally into the four-thickness zone- (see FIG. 3). The three thicknesses of metal are thus iirmly united. There is a venting of the side seam, air or gases within the seam escaping ahead -of the solder flow and into the interior of the can body by way of the space between the adjacent parts 36, 38. This insures a thoroughly sweated side seam in all sections.

In the four-thi-ckness zone of the side seam (FIG. 3), the solder 31 flows in over the can wall which is adjacent to and directly Aunder :the hook 36, this part of the seam being the portion pressed in during formation of the seam 24 and being designated by the numeral 34. This much of the solder 31 is under the inner or upper face of a hook 40 and joins the adjacent parts 34, 40. The solder then ows around the end of the hook 40 and in between the lower wall thereof and the upper face of the longitudinal hook 36, thus joining the adjacent parts 36, 40. Solder also flows in between the outside body wall adjacent its edge (designated by the numerals 38) and the outer or lower surface Aof the hook 36. This solder mostly enters :through the point where the three-thickness and -the four-thickness zones meet and spreads in both directions longitudinally of the seam from the opposite edges of the hooks 40 toward the middle of these hooks. Thus all four thicknesses of the metal making up the four-thickness zone of the sides seam are united by solder.

The solder 31 ows inwardly, uniting the parts of the side seam 24 and continues flowing until i-t forms a relatively large fillet 42, extending longitudinally along the interior of the container at the juncture of fthe side seam 24 and the body Wall 43. A coating of resin 44 which has been applied to the sheet metal prior to formation of the body 22, does not cover the molten solder 31 as it forms the fillet 42. However, this barrier layer of resin 44 lies over a layer of tin 45 and thereby covers lthe metallic container body 22 throughout the interior of the container 2t), except for the area covered by the substantially pure tin fillet 42 along the body interior adjacent the side seam 24.

The solder fillet 42, which is composed of substantially pure tin, rather than a solder alloy composition of 3% tin and 97% lead usually used in can side seams, is of suficient size to provide cathodic protection for any base steel exposed to the product such as at the can side seam or through imperfections in the resin coating 44 and underlying tin coating 45. Further, direct attack on the tin is substantially confined to fthe llet 42 which, in comparison to the tin coating 45, has a very high ratio of thickness to exposed surface area thereby maintaining the rate of direct attack on the tin at an acceptably low level. In order to provide this protection, the fillet 42 has a transverse width of about 0.3 to 1 mm. and a depth or thickness measured in the direction from its exposed surface towards the side seam folds of about 0.3 mm. A larger fillet will not extend the desired protection to Warrant the additional material cost, although the larger fillet is not objectionable from a functional standpoint.

The instant construction permits packaging of the relatively highly corrosive products specied herein with a relatively low interior tin coating weight, e.g. the surface tin coating over the substrate steel can be reduced from 1.35 lbs. per base box, i.e. No. 135 tin plate, to as low as 0.25 lb. per base box, i.e. No. tin plate. This is possible because in the subject construction, unlike the prior art, the surface tin coating 45 is not subjected to direct attack by the product nor is it the primary source of cathodic protection for the steel since it is covered substantially completely by the resin coating 44. The primary source of cathodic protection is, of course, the iillet 42, and is only relatively slightly attacked directly by the product due to its relatively small exposed surface area.

Within the container 20 is the product 46. The product 46 is a comestible and, as pointed out previously, is relatively highly corrosive to the Imetal of the can 20. Among the comestible products 46 Within the purview of the instant invention are tannate-containing products such as asparagus, green beans, okra and cranberries; tornato products such as tomatoes, tornato puree and tornato paste; and prunes. After filling the product 46 into lthe Icontainer comprising the body 22 and one end closure, either 25 or 26, the opposite end closure is secured to the body 22 by a well-known doubleseaming operation so that the product 46 is then hermetically sealed within the can 20.'

It is thought that the invention and many of its attendant advantages -Will be understood from the foregoing description, and it will be apparent -that various changes may be made in the form, construction and arrangement of the parts without departing from the scope of the invention or sacrificing all of its material advantages, the form hereinbefore described being merely a preferred embodiment thereof.

decenas I claim: y Y

1. A container for packaging a relatively corrosive comestible which directly attacks both tin and steel comprising:

a tubular tinplate metal body closed at one end and open at its opposite end;

said body having a longitudinally extending side seam substantially filled and hermetically sealed with sublstantially pure tin Isolder;

said solder extending inwardly of said side seam to form a fillet having a transverse width of at least about 0.3 mm. and a depth of at least about 0.3 mm. along said side seam on the interior of the body at the juncture of said side seam and the side wall of said body;

the entire interior surface of said body and end closure,

except for said fillet, being'covered with a resin coatmg;

said fillet having a substantially larger ratio of thickness to exposed surface area than the interior tinplating on said body prior to the coating thereof with said resin whereby cathodic protection of the substrate steel is provided by said iillet and direct attack on the tin and steel of said container by said comestible is confined essentially to said fillet.

2. The container set forth in claim 1 wherein said fillet has a transverse Width of about 0.3 to 1 mm. and a depth of about 0.3 mm. Y

3. The container set forth in claim 2 wherein said tinplating thickness is less than No. tinplate.

4. The container set forth in claim 3 wherein said tinplating thickness is No. 25 tinplate.

5. A package comprising a container and a relatively corrosive comestible therein which directly attacks both tin and steel;

said container comprising a tubular tinpiate body hermetically closed and sealed at each end;

said body having a longitudinally extending side seam substantially filled and hermetically sealed Vwith a substantially pure tin solder;

the entire interior surface of said body and end closures,

except for said fillet, being covered with a resin coating;

said fillet having a substantially larger ratio of thickness to exposed surface area than the interior tinplating on said body prior to the coating thereof with said resin whereby cathodic protection of the substrate steel is provided -by said fillet and direct attack on the tin and steel of said container by said comestible is confined essentially to said llet.

6. The package set forth in claim 5 wherein said comestible is selected from the group consisting of okra, cranberries, asparagus, green beans, tomato prod-ucts and prunes.

7. The package set forth in claim 6 wherein said comestible is tomato paste.

References Cited by the Examiner UNITED STATES PATENTS 1,030,358 6/1912 Weber 220-81 2,064,537 12/1936 Groenke 220-75 2,092,296 9/ 1937 Voorhees 99-181 2,163,619 6/1939 Murch 220-75 2,741,397 4/ 1956 Shotton 220-64 2,797,023 6/ 1957 Kaearcher et al. 220-64 2,918,377 12/1959 Hurley et al. 99-171 2,965,496 lt2/l960 Serdar 99-171 3,040,781 6/ 1962 Reymann et al. 220-64 X A. LOUIS MONACELL, Primary Examiner.

RAYMOND N. JONES, Examiner. 

1. A CONTAINER FOR PACKAGING A RELATIVELY CORROSIVE COMESTIBLE WHICH DIRECTLY ATTACKS BOTH TIN AND STEEL COMPRISING: A TUBULAR TINPLATE METAL BODY CLOSED AT ONE END AND OPEN AT ITS OPPOSITE END; SAID BODY HAVING A LONGITUDINALLY EXTENDING SIDE SEAM SUBSTANTIALLY FILLED AND HERMETICALLY SEALED WITH SUBSTANTIALLY PURE TIN SOLDER; SAID SOLDER EXTENDING INWARDLY OF SAID SIDE SEAM TO FORM A FILLET HAVING A TRANSVERSE WIDTH OF AT LEAST ABOUT 0.3 MM. AND A DEPTH OF AT LEAST ABOUT 0.3 MM, ALONG SAID SIDE SEAM ON THE INTERIOR OF THE BODY AT THE JUNCTURE OF SAID SIDE SEAM AND THE SIDE WALL OF SAID BODY; THE ENTIRE INTERIOR SURFACE OF SAID BODY AND END CLOSURE, EXCEPT FOR SAID FILLET, BEING COVERED WITH A RESIN COATING; SAID FILLET HAVING A SUBSTANTIALLY LARGER RATIO OF THICKNESS TO EXPOSED SURFACE AREA THAN THE INTERIOR TINPLATING ON SAID BODY PRIOR TO THE COATING THEREOF WITH SAID RESIN WHEREBY CATHODIC PROTECTION OF THE SUBSTRATE STEEL IS PROVIDED BY SAID FILLET AND DIRECT ATTACK ON THE TIN AND STEEL OF SAID CONTAINER BY SAID COMESTIBLE IS CONFINED ESSENTIALLY TO SAID FILLET. 